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Genetics > Exam 1: Lecture 6 & 7 > Flashcards

Exam 1: Lecture 6 & 7 Flashcards

1
Q

define genetic linkage

A

tendency of alleles that are located close together on a chromosome to be inherited together during meiosis linked genes will segregate togehter and not obery mendels 2nd law

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2
Q

linkage disequilibrium

A

the non-random association of alleles at diff loci

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3
Q

what can restore random segregation

A

meiosis/recombination

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4
Q

what are complex inheritance of traits

A

some traits, like human stature, are produced by the interplay of many sets of genes; these are known as “polygenic” traits

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5
Q

what is a single gene disorder

A

single mutated gene causes a disorder

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6
Q

what is non-mendelian inheritance

A

any pattern of inheritance in which traits do not segregate with mendel’s laws

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7
Q

snail chirality

A

is based on determining polarity in early embryo; earliest and important events in embryo development

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8
Q

genes at the same locus

A

two versions of the same gene; each version of the same gene is defined as allele ex blood type

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9
Q

mendel’s traits all exhibited _

A

complete dominance

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10
Q

define complete dominance

A

phenotype of the heterozygote is the same as the phenotype of homozygous dominant

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11
Q

define incomplete dominance

A

phenotype of the heterozygote is intermediate (fails w/in the range) btwn the phenotypes of the two homozygotes

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12
Q

define codominance

A

phenotype of the heterozygote includes the phenotypes of both homozygotes

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13
Q

define penetrance

A

percentage of individuals having a particular genotype that expresses the expected phenotype

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14
Q

expressivity

A

the degree to which a character is expressed

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15
Q

complete penetrance

A

everyone who inherits the disease causing alleles has symptoms ex DMD

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16
Q

incomplete penetrance

A

some indivs do not express the phenotype even though they inherit the alleles ex polydactlyly

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17
Q

variable expression

A

symptoms vary in intensity in diff ppl ex 2 extra digits vs 3 extra digits in polydactlyly

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18
Q

_ and the _ who contributed the mutation affect the risk (penetrance)

A

sex and the parent who contributed

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19
Q

lethal alleles cause what on mendelian genotypic and phenotypic ratios in progeny

A

cause progeny to die so some genotypes may not appear among the progeny producing skewed ratios

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20
Q

what is an example of multiple alleles

A

ABO blood group; for a given locus, more than 2 alleles are present w/in a group of indivs

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21
Q

which blood type is codominant?

A

AB

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22
Q

what is gene interaction

A

interaction btwn alleles; interaction btwn 2 loci determine a single characteristic

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23
Q

gene interaction can produce _ phenotypes

A

novel

24
Q

define gene interaction and describe gene interaction with epistasis

A

gene interaction effects of genes at one locus depend on the presence of genes at other loci and w/ epistasis one gene masks the effect of another gene

25
Q

epistasis

A

interaction of genes that are not alleles in particular, one gene masks or influences the effect of another gene

26
Q

recessive epistasis

A

a recessive mutation in one gene masks the phenotypic effects of another
when the recessive allele of one gene masks the effect of either allele of the second gene

27
Q

dominant epistasis

A

when the dominant allele of one gene masks the expression of all alleles of another gene

28
Q

pleiotropy

A

one gene is able to affect multiple phenotypic characteristics ex sickle-cell disease and capillaries in eye, liver, and heart

29
Q

complementation

A

2 strains of an organism with diff homozygous recessive mutations that produce the same mutant phenotype and produce offspring with the WT phenotype when mated or crossed

30
Q

crossing pure breeding strains result in the mutant phenotype if

A

the mutations occur at a single locus

31
Q

crossing pure breeding strains results in a wild type phenotype if

A

the mutations occur at different loci; WT masks mutant

32
Q

in cystic fibrosis, why is disease symptoms viewed as complete dominance

A

a heterozygous CF carrier don’t usu exhibit symptoms of CF; the normal and disease alleles show complete dominance

33
Q

in cystic fibrosis, why is channel localizations viewed as codominant

A

at the cellular level, there will be normal channels at the membrane (from the normal allele) and trapped channels in the ER (from disease allele) ie both present

34
Q

in cystic fibrosis, why is chloride transport viewed as incomplete dominance

A

the disease and normal alleles of CF may show chloride in sweat slightly above normal in heteros but not abnormal enough compared to homos

35
Q

sex influenced traits

A

controlled by genes present on autosomes and expression responds differently to androgens or estrogens

36
Q

sex-limited characteristics are inherited according to

A

mendel’s principles; ex precocious puberty in humans. both male and female can transmit this sex limited trait, but it is expressed only in males

37
Q

imprinted genes

A

are genes whose expression is determined by the parent that contributed them

38
Q

genomic imprinting

A

certain genes are expressed in a parent-of-origin-specific manner; depending on if you are m/f, certain genes are modified based on your sex ex IGF2 locus paternal is active and maternal allele non-functional. SIGNIFICANT DEVIATION FROM MENDEL’S RULES

39
Q

epigenetics

A

alterations to DNA that do not include changes in the base sequence; affect how DNA sequences are expressed

40
Q

imprinting phenomenon increases with

A

organisms becoming more complex

41
Q

epigentic trait

A

ex IGF2 gene; not a consequence of changes in DNA sequence. “stably heritable”

42
Q

stably heritable mean

A

passed from one generation to the next and at the level of mitosis (mother to daughter cell)

43
Q

genetic phenomenon: sex-linked characteristic

A

phenotype determined by: genes located on the sex chromosome

44
Q

genetic phenomenon: sex-influenced characteristic

A

phenotype determined by: autosomal genes that are more readily expressed in one sex

45
Q

genetic phenomenon: sex-limited characteristic

A

phenotype determined by: autosomal genes whose expression is limited to one sex

46
Q

genetic phenomenon: genetic maternal effect

A

phenotype determined by: nuclear genotype of the maternal parent

47
Q

genetic phenomenon: cytoplasmic inheritance

A

phenotype determined by: cytoplasmic genes, which are usually inherited from only one parent

48
Q

genetic phenomenon: genomic imprinting

A

phenotype determined by: genes whose expression is affected by the sex of the transmitting parent

49
Q

what is anticipation

A

COMMON PHENOTYPIC DISORDER AND DIFFERENT FROM MENDEL’S RULES

genetic trait becomes more strongly expressed or expressed at an earlier stage as it is passed from generation to generation

50
Q

how does anticipation occur

A

slippage in recombination, repetitive aas are incorporated in protein in blocks (3 nucleotides) causing duplications in regions (accumulation/expansion)

51
Q

Fragile X mental retardation, why is it rare in females

A

FMR1 located on x chromosome thus more common in males bc an affected father and carrier mother which almost never happens bc of the impairment associated with it

52
Q

discontinuous characteristics

A

relatively few phenotypes

53
Q

continuous characteristics

A

continuous distribution of phenotypes; occurs when genes at many loci interact ex skin pigmentation

54
Q

polygenic characteristics

A

result of many genes (genes at many loci) contributing to characteristics ex skin pigmentation

55
Q

multifactorial traits/complex disorders

A

accumulation of variants of multiple genes and as they passed along in a family; influenced by a greater degree by environment

56
Q

heterosis or hybrid vigor

A

importance in variation in a genome. Having 2 different alleles (hetero) is better for variation and in hybrids; hybrids are better than pure (homo) breeding ex mule

Genetics (37 decks)

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